Question

Tìm x

|7x+1|=20

Chính xác tick ngay và luôn

 

Answer 1

|7x + 1| = 20

+) 7x + 1 = 20

=> 7x = 19

=> x = 19/7

+) 7x + 1 = -20

=> 7x = -21

=> x = -21 : 7

=> x = -3

Vậy x \(\in\){-3; 19/7}.

Answer 2

7x+1=+_20

7x= 19 hoặc -21

7x=-21

x=-3

Answer 3

|7x+1|=20

7x+1=20 hoac 7x+1=-20

7x+1=20

7x=20-1

7x=19=>x=19/7

7x+1=-20

7x=-20-1

7x=-21=>x=-3

Vay x=19/7;x=-3

 Tick nha!

Answer 4

l7x+1l=20

\(\Leftrightarrow\)7x+1=20 hoac 7x+1=-20

TH1:

7x+1=20

\(\Leftrightarrow\)7x=20-1=19

\(\Leftrightarrow\)x=19:7=\(\frac{19}{7}\)

TH2:

7x+1=-20

\(\Leftrightarrow\)7x=-20-1=-21

\(\Leftrightarrow\)x=-21:7=-3

Vay x= \(\frac{19}{7};-3\)

 

Answer 5

       /7x+1/=20

--> 7x+1=+-20

th1    7x+1=20--->x=19/7

TH2   7x+1=-20-->x=-3